Organic light emitting diode display device and method of fabricating the same

ABSTRACT

An organic light emitting diode display device, and method of fabricating an organic light emitting diode display device are discussed. The organic light emitting diode display device according to one embodiment includes a first electrode on a thin film transistor and connected to a drain electrode; an auxiliary electrode on a same layer as the first electrode; a bank layer covering edges of the first electrode and edges of the auxiliary electrode and having a transmissive hole corresponding and an auxiliary contact hole; a light emitting layer on the first electrode in the transmissive hole; a residual layer on the auxiliary electrode in the auxiliary contact hole. A central portion of the residual layer has a larger thickness than an edge portion of the residual layer. The organic light emitting diode display device further includes a second electrode on the light emitting layer and the residual layer.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the priority benefit of Korean PatentApplication No. 10-2014-0129522 filed in the Republic of Korea on Sep.26, 2014, the entire contents of which are hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Disclosure

The present disclosure relates to an organic light emitting diodedisplay device, and more particularly, to an organic light emittingdiode display device and a method of fabricating the same. The organiclight emitting diode display device provides uniform brightness and hasa large size and high definition.

2. Description of the Related Art

Recently, flat panel displays have been widely developed and applied tovarious fields because of their thin profile, light weight, and lowpower consumption. Among the flat panel displays, organic light emittingdiode (OLED) display devices, which can be referred to as organicelectroluminescent display devices, emit light during loss ofelectron-hole pairs. The electron-hole pairs are formed by injectingcharges into a light emitting layer between a cathode for injectingelectrons and an anode for injecting holes.

The OLED display device can be self-luminous and include a flexiblesubstrate such as plastic. The self-luminous OLED display device canhave an excellent contrast ratio and a response time of several microseconds. The self-luminous OLED display device has advantages indisplaying moving images including a displaying the moving images at awide viewing angle and being stable under low temperatures. Theself-luminous OLED display device can be driven by a low voltage ofdirect current (DC) 5V to 15V, and, as a result, driving circuits in theOLED display can be easily designed and manufactured. In addition,manufacturing processes of the OLED display device can be simple becauseonly deposition and encapsulation steps are required.

In addition, OLED display devices according to driving methods can bepassive matrix type OLED display devices and active matrix type OLEDdisplay devices. Active matrix type display devices have low powerconsumption and high definition. In addition, the size of active matrixtype display devices can be large.

FIG. 1 is a circuit diagram of one pixel region of an OLED displaydevice according to the related art. The OLED display device includes agate line GL, a data line DL, a switching thin film transistor Ts, adriving thin film transistor Td, a storage capacitor Cst and a lightemitting diode De. The gate line GL and the data line DL cross eachother to define a pixel region P. The switching thin film transistor Ts,the driving thin film transistor Td, the storage capacitor Cst and thelight emitting diode De are formed in the pixel region P.

More particularly, a gate electrode of the switching thin filmtransistor Ts is connected to the gate line GL and a source electrode ofthe switching thin film transistor Ts is connected to the data line DL.A gate electrode of the driving thin film transistor Td is connected toa drain electrode of the switching thin film transistor Ts, and a sourceelectrode of the driving thin film transistor Td is connected to a highvoltage supply VDD. An anode of the light emitting diode De is connectedto a drain electrode of the driving thin film transistor Td, and acathode of the light emitting diode De is connected to a low voltagesupply VSS. The storage capacitor Cst is connected to the gate electrodeand the drain electrode of the driving thin film transistor Td.

The OLED display device can be operated to turn on switching thin filmtransistor Ts by a gate signal applied through the gate line GL. Theswitching thin film transistor Ts can be turned on to apply a datasignal from the data line DL to the gate electrode of the driving thinfilm transistor Td and an electrode of the storage capacitor Cst throughthe switching thin film transistor Ts. When the driving thin filmtransistor Td is turned on by the data signal, an electric currentflowing through the light emitting diode De is controlled, therebydisplaying an image. The light emitting diode De emits light due to thecurrent supplied through the driving thin film transistor Td from thehigh voltage supply VDD.

Namely, the amount of the current flowing through the light emittingdiode De is proportional to the magnitude of the data signal, and theintensity of light emitted by the light emitting diode De isproportional to the amount of the current flowing through the lightemitting diode De. Thus, the pixel regions P show different gray levelsdepending on the magnitude of the data signal, and as a result, the OLEDdisplay device displays an image.

The storage capacitor Cst maintains charges corresponding to the datasignal for a frame when the switching thin film transistor Ts is turnedoff. Accordingly, even if the switching thin film transistor Ts isturned off, the storage capacitor Cst allows the amount of the currentflowing through the light emitting diode De to be constant and the graylevel shown by the light emitting diode De to be maintained until a nextframe.

OLED display devices include bottom emission type OLED display devicesand top emission type OLED display devices depending on an emissiondirection. In the bottom emission type OLED display devices, lightemitted from the light emitting diode is output toward a substrate,where the thin film transistors are formed, through the anode. In thetop emission type OLED display devices, light emitted from the lightemitting diode is output toward a direction opposite to the substratethrough the cathode.

In the OLED display devices, the thin film transistors, generally, areformed under the light emitting diode, and in the bottom emission typeOLED display device, an effective emission area is limited by the thinfilm transistors. The top emission type OLED display device has a largereffective emission area than the bottom emission type OLED displaydevice. Therefore, the top emission type OLED display device has arelatively high aperture ratio as compared with the bottom emission typeOLED display device. In addition, the top emission type OLED displaydevice can have a large size and high definition.

In addition, the cathode can be formed of a metallic material. In thetop emission type OLED display device, the cathode needs to have arelatively thin thickness to output light through the cathode. As aresult, a resistance of the cathode increases, and a VSS voltage dropoccurs, thereby causing non-uniform brightness.

SUMMARY OF THE INVENTION

Accordingly, the present disclosure is directed to an organic lightemitting diode display device and a method of fabricating the same thatsubstantially obviate one or more of the problems due to limitations anddisadvantages of the related art. An object of the present disclosure isto provide an organic light emitting diode display device having a largesize, a high definition and a uniform brightness, and a method offabricating the organic light emitting diode display device.

Additional features and advantages of these embodiments will be setforth in the description which follows, and in part will be apparentfrom the description, or can be learned by practice of the embodiments.The objectives and other advantages will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present disclosure, as embodied and broadly described herein,according to one or more embodiments, an organic light emitting diodedisplay device includes a substrate; a thin film transistor on thesubstrate; a first electrode connected to a drain electrode of the thinfilm transistor; an auxiliary electrode on a same layer as the firstelectrode; a bank layer covering edges of the first electrode and edgesof the auxiliary electrode and having a transmissive hole correspondingto the first electrode and an auxiliary contact hole corresponding tothe auxiliary electrode; a light emitting layer on the first electrodein the transmissive hole; a residual layer on the auxiliary electrode inthe auxiliary contact hole. The residual layer has a thicknessincreasing from a central portion to an edge portion. The organic lightemitting diode display device further includes a second electrode on thelight emitting layer and the residual layer.

In another aspect, a method of fabricating an organic light emittingdiode display device includes forming a thin film transistor on asubstrate; forming a passivation layer on the thin film transistor;forming a first electrode and an auxiliary electrode on the passivationlayer, the first electrode connected to a drain electrode of the thinfilm transistor, and the auxiliary electrode spaced apart from the firstelectrode; forming a bank layer having a transmissive hole exposing thefirst electrode and an auxiliary contact hole exposing the auxiliaryelectrode; sequentially forming a hole injecting material layer and ahole transporting material layer over substantially all of the substrateincluding the bank layer; forming a light emitting material layer on thehole transporting material layer corresponding to the transmissive hole;sequentially forming an electron transporting material layer and anelectron injecting material layer over substantially all of thesubstrate including the light emitting material layer; melting anddrying the electron injecting material layer, the electron transportingmaterial layer, the hole transporting material layer and the holeinjecting material layer corresponding to the auxiliary contact holeusing an organic solvent, thereby forming a hole injecting layer, a holetransporting layer, an electron transporting layer and an electroninjecting layer corresponding to the light emitting material layer andforming a residual layer on the auxiliary electrode in the auxiliarycontact hole. The residual layer has a thickness increasing from acentral portion to an edge portion. The method further includes forminga second electrode on the electron injecting layer and the residuallayer.

In another aspect, a method of fabricating an organic light emittingdiode display device includes forming a thin film transistor on asubstrate; forming a passivation layer on the thin film transistor;forming a first electrode and an auxiliary electrode on the passivationlayer, the first electrode connected to a drain electrode of the thinfilm transistor, and the auxiliary electrode spaced apart from the firstelectrode; forming a bank layer having a transmissive hole exposing thefirst electrode and an auxiliary contact hole exposing the auxiliaryelectrode; sequentially forming a hole injecting layer, a holetransporting layer and a first light emitting material layer on thefirst electrode exposed by the transmissive hole; sequentially forming asecond light emitting material deposition layer, an electrontransporting material layer and an electron injecting material layerover substantially all of the substrate including the first lightemitting material layer; melting and drying the electron injectingmaterial layer, the electron transporting material layer, and the secondlight emitting material deposition layer corresponding to the auxiliarycontact hole using an organic solvent, thereby forming a second lightemitting material layer, an electron transporting layer and an electroninjecting layer corresponding to the first light emitting material layerand forming a residual layer on the auxiliary electrode in the auxiliarycontact hole. The residual layer has a thickness increasing from acentral portion to an edge portion. The method further includes forminga second electrode on the electron injecting layer and the residuallayer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory. Theforegoing general description and the following detailed description areintended to provide further explanation of the embodiments as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a circuit diagram of one pixel region of an OLED displaydevice according to the related art;

FIG. 2 is a cross-sectional view of an OLED display device according toa first embodiment of the present disclosure;

FIGS. 3A to 3H are cross-sectional views of an OLED display device insteps of fabricating the display device according to the firstembodiment of the present disclosure;

FIG. 4 is a cross-sectional view of an OLED display device according toa second embodiment of the present disclosure;

FIG. 5 is a cross-sectional view of an OLED display device according toa third embodiment of the present disclosure;

FIG. 6 and FIG. 7 are cross-sectional views of an OLED display deviceaccording to a fourth embodiment of the present disclosure; and

FIGS. 8A to 8F are cross-sectional views of an OLED display device insteps of fabricating the display device according to the fourthembodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments,examples of which are illustrated in the accompanying drawings.

FIG. 2 is a cross-sectional view of an OLED display device according toa first embodiment of the present disclosure. The OLED display deviceaccording to the first embodiment includes one pixel region and asemiconductor layer 122 formed on an insulating substrate 110. Thesubstrate 110 can be a glass substrate or a plastic substrate. Thesemiconductor layer 122 can be formed of an oxide semiconductormaterial. In addition, the OLED display device including thesemiconductor layer 122 formed of an oxide semiconductor material caninclude a light-blocking pattern and a buffer layer formed under thesemiconductor layer 122. The light-blocking pattern blocks light fromthe outside or light emitted from a light emitting diode to prevent thesemiconductor layer 122 from being degraded by the light. Alternatively,the semiconductor layer 122 can be formed of polycrystalline silicon,and in this case, impurities can be doped in both ends of thesemiconductor layer 122.

A gate insulating layer 130 of an insulating material is formed on thesemiconductor layer 122 over substantially all of the substrate 110. Thegate insulating layer 130 can be formed of an inorganic insulatingmaterial such as silicon oxide (SiO₂). When the semiconductor layer 122is formed of polycrystalline silicon, the gate insulating layer 130 canbe formed of an inorganic insulating material such as silicon oxide(SiO₂) and silicon nitride (SiN_(x)).

A gate electrode 132 of a conductive material such as metal can beformed on the gate insulating layer 130 to correspond to thesemiconductor layer 122. In addition, a gate line and a first capacitorelectrode can be formed on the gate insulating layer 130. The gate lineextends in a first direction, and the first capacitor electrode can beconnected to the gate electrode 132. In addition, the OLED displaydevice according to the first embodiment of the present disclosureincludes the gate insulating layer 130 formed over substantially all ofthe substrate 110. Alternatively, the gate insulating layer 130 can bepatterned to have the same shape as the gate electrode 132.

An inter insulating layer 140 of an insulating material is formed on thegate electrode 132 over substantially all of the substrate 110. Theinter insulating layer 140 can be formed of an inorganic insulatingmaterial such as silicon oxide (SiO₂) and silicon nitride (SiN_(x)) oran organic insulating material such as benzocyclobutene and photo acryl.

The inter insulating layer 140 includes first and second contact holes140 a and 140 b exposing top surfaces of both sides of the semiconductorlayer 122. The first and second contact holes 140 a and 140 b are spacedapart from the gate electrode 132, and the gate electrode 132 isdisposed between the first and second contact holes 140 a and 140 b. Thefirst and second contact holes 140 a and 140 b are also formed in thegate insulating layer 130. Alternatively, when the gate insulating layer130 is patterned to have the same shape as the gate electrode 132, thefirst and second contact holes 140 a and 140 b are formed only in theinter insulating layer 140.

A source electrode 152 and a drain electrode 154 of a conductivematerial such as metal are formed on the inter insulating layer 140. Inaddition, a data line, a power supply line and a second capacitorelectrode can be formed on the inter insulating layer 140. The data lineand the power supply line extend in a second direction.

The source and drain electrodes 152 and 154 are spaced apart from eachother with respect to the gate electrode 132. The source and drainelectrodes 152 and 154 contact both sides of the semiconductor layer 122through the first and second contact holes 140 a and 140 b,respectively. The data line can cross the gate line to define a pixelregion. In addition, the power supply line can be spaced apart from thedata line. The second capacitor electrode can be connected to the drainelectrode 154 and can overlap the first capacitor electrode to form astorage capacitor with the inter insulating layer 140 therebetween as adielectric substance.

In the OLED display device, a thin film transistor includes thesemiconductor layer 122, the gate electrode 132, the source electrode152 and the drain electrode 154. The thin film transistor can have acoplanar structure where the gate electrode 132 and the source and drainelectrodes 152 and 154 are disposed at sides of the semiconductor layer122, over the semiconductor layer 122.

Alternatively, the thin film transistor can have an inverted staggeredstructure where the gate electrode is disposed under the semiconductorlayer and the source and drain electrodes are disposed over thesemiconductor layer. In this case, the semiconductor layer can be formedof amorphous silicon. In addition, the thin film transistor can be adriving thin film transistor of the OLED display device. A switchingthin film transistor can have the same structure as the driving thinfilm transistor formed over the substrate 110. At this time, the gateelectrode 132 of the driving thin film transistor is connected to adrain electrode of the switching thin film transistor, and the sourceelectrode 152 of the driving thin film transistor is connected to thepower supply line. In addition, the gate electrode and the sourceelectrode of the switching thin film transistor are connected to thegate line and the data line, respectively.

A passivation layer 160 of an insulating material is formed on thesource and drain electrodes 152 and 154 over substantially all of thesubstrate 110. The passivation layer 160 has a flat top surface and hasa drain contact hole 160 a exposing the drain electrode 154. In FIG. 2,although the drain contact hole 160 a is formed directly over the secondcontact hole 140 b, the drain contact hole 160 a can be spaced apartfrom the second contact hole 140 b.

The passivation layer 160 can be formed of an organic insulatingmaterial such as benzocyclobutene and photo acryl. A first electrode 162of a conductive material having a relatively high work function isformed on the passivation layer 160. The first electrode 162 is disposedin each pixel region and contacts the drain electrode 154 through thedrain contact hole 160 a. For example, the first electrode 162 can beformed of a transparent conductive material such as indium tin oxide(ITO) and indium zinc oxide (IZO).

The first electrode 162 can further include a reflective layer of anopaque conductive material. For example, the reflective layer can beformed of aluminum-paladium-copper (APC) alloy, and the first electrode162 can have a triple-layered structure of ITO/APC/ITO.

In addition, an auxiliary electrode 164 is formed on the passivationlayer 160 and spaced apart from the first electrode 162. The auxiliaryelectrode 164 can be formed of the same material as the first electrode162. The auxiliary electrode 164 can extend in the first direction andthe second direction over the substrate 110 and include an openingcorresponding to each pixel region to have a lattice shape. The firstelectrode 162 can be disposed in the opening of the auxiliary electrode164.

A bank layer 170 of an insulating material is formed on the firstelectrode 162 and the auxiliary electrode 164. The bank layer 170 has atransmissive hole 170 a and an auxiliary contact hole 170 b. The banklayer 170 covers edges of the first electrode 162 and edges of theauxiliary electrode 164. The transmissive hole 170 a exposes the firstelectrode 162, and the auxiliary contact hole 170 b exposes theauxiliary electrode 164.

A light emitting layer 180 is formed on the first electrode 162 exposedby the transmissive hole 170 a of the bank layer 170. The light emittinglayer 180 includes a hole injecting layer 181, a hole transporting layer182, a light emitting material layer 183, an electron transporting layer184, and an electron injecting layer 185 sequentially layered on thefirst electrode 162. The hole injecting layer 181, the hole transportinglayer 182, the electron transporting layer 184 and the electroninjecting layer 185 are formed over substantially all of the substrate110 excluding the auxiliary contact hole 170 b. The light emittingmaterial layer 183 is formed only in the transmissive hole 170 a. Thelight emitting material layer 183 can be one of red, green and bluelight emitting material layers.

A residual layer 187 is formed in the auxiliary contact hole 170 b. Acentral portion of the residual layer 187 is smaller than an edgeportion thereof in the auxiliary contact hole 170 b. The thickness ofthe edge portion of the residual layer 187 can be 1.1 times or more thanthe thickness of the central portion of the residual layer 187.Beneficially, the thickness of the edge portion of the residual layer187 may be more than 10 times as thick as the thickness of the centralportion of the residual layer 187. For example, the thickness of thecentral portion of the residual layer 187 can be less than 200 Å.

The hole injecting layer 181, the hole transporting layer 182, the lightemitting material layer 183, the electron transporting layer 184 and theelectron injecting layer 185 can be formed of an organic material.Alternatively, the electron injecting layer 185 can be formed of aninorganic material. The inorganic material, for example, can be sodiumfluoride (NaF). In this case, the residual layer 187 substantiallyincludes an inorganic material.

A second electrode 192 of a conductive material having relatively lowwork function is formed on the light emitting layer 180 oversubstantially all of the substrate 110. Here, the second electrode 192can be formed of aluminum (Al), magnesium (Mg), silver (Ag) or theiralloy. The second electrode 192 can have a relatively thin thicknesssuch that light is transmitted therethrough. At this time, thetransmittance of the second electrode 192 can be about 45 to 50%.

The second electrode 192 is electrically connected to the auxiliaryelectrode 164 through the auxiliary contact hole 170 b. The secondelectrode 192 can directly contact the auxiliary electrode 164 orindirectly contact the auxiliary electrode 164 through the residuallayer 187. The first electrode 162, the light emitting layer 180 and thesecond electrode 192 constitute an organic light emitting diode. Thefirst electrode 162 functions as an anode, and the second electrode 192serves as a cathode. Here, the OLED display device is a top emissiontype in which light from the light emitting layer 180 is output to theoutside through the second electrode 192.

In the OLED display device according to the first embodiment of thepresent disclosure, the second electrode 192 is connected to theauxiliary electrode 164, and the resistance of the second electrode 192is lowered. At this time, the second electrode 192 can be connected tothe auxiliary electrode 164 through a simple process by removing thehole injecting layer 181, the hole transporting layer 182, the electrontransporting layer 184, and the electron injecting layer 185 in theauxiliary contact hole 170 b using an organic solvent.

When a thin film is disposed between the second electrode 192 and theauxiliary electrode 164, the electrical connection between the secondelectrode 192 and the auxiliary electrode 164 depending on the thicknessof the thin film will be explained with reference to Table 1.

Table 1 shows resistance of the electron injecting layer between theauxiliary electrode and the second electrode.

TABLE 1 NaF thickness ITO/NaF/Ag resistance S1  50 Å  77 Ω S2  300 Å 101Ω S3 1000 Å several MΩ

For example, an ITO layer of 500 Å is formed over the substrate as theauxiliary electrode, a NaF layer of 50 Å (S1), 300 Å (S2) or 1,000 Å(S3) is formed over the ITO layer as the electron injecting layer, andan Ag layer of 500 Å is formed over the NaF layer as the secondelectrode. A resistance meter, which can be referred to as an ohmmeter,is connected to the ITO layer and the Ag layer, and the resistancebetween the ITO layer and the Ag layer is measured depending on thethickness of the NaF layer. Here, the NaF layer and the Ag layer can beformed by a deposition method, and prevent an electrical short betweenthe Ag layer and the ITO layer, an insulating tape can be disposed inedges of an area where the NaF layer and the Ag layer are deposited.

As shown in Table 1, when the NaF layer 50 Å (S1), the resistancebetween the ITO layer and the Ag layer is 77 ohms, and when the NaFlayer 300 Å (S2), the resistance between the ITO layer and the Ag layeris 101 ohms. Thus, it is noted that the ITO layer and the Ag layer areelectrically connected to each other. On the other hand, when the NaFlayer is 1,000 Å (S3), the resistance between the ITO layer and the Aglayer is several mega ohms, and the ITO layer and the Ag layer are notelectrically connected to each other. Accordingly, although the residuallayer 187 is disposed between the second electrode 192 and the auxiliaryelectrode 164, the thickness of the residual layer 187 is less than 200Å, and the second electrode 192 and the auxiliary electrode 164 areelectrically connected to each other.

Next, FIGS. 3A to 3H are cross-sectional views of an OLED display devicein steps of fabricating the display device according to the firstembodiment of the present disclosure. Referring to FIG. 3A, asemiconductor material layer can be formed on an insulating substrate110 by depositing a semiconductor material, and the semiconductormaterial layer is selectively removed through a photolithographicprocess using a mask, thereby forming a semiconductor layer 122.

Here, the insulating substrate 110 can be a glass substrate or a plasticsubstrate. In addition, the semiconductor layer 122 can be formed of anoxide semiconductor material. The oxide semiconductor material can beindium gallium zinc oxide (IGZO), indium tin zinc oxide (ITZO), indiumzinc oxide (IZO), zinc oxide (ZnO), indium gallium oxide (IGO) or indiumaluminum zinc oxide (IAZO). At this time, a light-blocking pattern and abuffer layer can be further formed under the semiconductor layer 122.Alternatively, the semiconductor layer 122 can be formed ofpolycrystalline silicon,

Next, a gate insulating layer 130 is formed on the semiconductor layers122 by depositing an insulating material over substantially all of thesubstrate 110 by a chemical vapor deposition method, for example. Thegate insulating layer 130 can be formed of an inorganic insulatingmaterial such as silicon oxide (SiO₂) and silicon nitride (SiN_(x)).When the semiconductor layer 122 is formed of an oxide semiconductormaterial, the gate insulating layer 130, beneficially, can be of siliconoxide (SiO₂).

Then, a first conductive material layer can be formed on the gateinsulating layer 130 by depositing a conductive material such as metalby a sputtering method, for example, and the first conductive materiallayer can be selectively removed through a photolithographic processusing a mask, thereby forming a gate electrode 132. The gate electrode132 has a narrower width than the semiconductor layer 122 and isdisposed to correspond to a central part of the semiconductor layer 122.The gate electrode 132 can be formed of at least one of aluminum (Al),copper (Cu), molybdenum (Mo), chromium (Cr), nickel (Ni), tungsten (W),and an alloy thereof.

A first capacitor electrode and a gate line are formed simultaneouslywith the gate electrode 132. The first capacitor electrode can beconnected to the gate electrode 132, and the gate line can extend in afirst direction. Next, an inter insulating layer 140 is formed on thegate electrode 132 by depositing or applying an insulating material oversubstantially all of the substrate 110, and the inter insulating layer140 and the gate insulating layer 130 are selectively removed through aphotolithographic process using a mask, thereby forming first and secondcontact holes 140 a and 140 b. The first and second contact holes 140 aand 140 b expose top surfaces of both sides of the semiconductor layer122, respectively. The first and second contact holes 140 a and 140 bare spaced apart from the gate electrode 132, and the gate electrode 132is disposed between the first and second contact holes 140 a and 140 b.The inter insulating layer 140 can be formed of an inorganic insulatingmaterial such as silicon oxide (SiO₂) and silicon nitride (SiN_(x)) oran organic insulating material such as benzocyclobutene and photo acryl.

Next, a second conductive material layer can be formed on the interinsulating layer 140 by depositing a conductive material such as metalby a sputtering method, for example, and the second conductive materiallayer can be selectively removed through a photolithographic processusing a mask, thereby forming source and drain electrodes 152 and 154.The source and drain electrodes 152 and 154 are spaced apart from eachother with respect to the gate electrode 132. The source and drainelectrodes 152 and 154 contact both sides of the semiconductor layer 122through the first and second contact holes 140 a and 140 b,respectively.

The source and drain electrodes 152 and 154 can be formed of at leastone of aluminum (Al), copper (Cu), molybdenum (Mo), chromium (Cr),nickel (Ni), tungsten (W), and an alloy thereof. A data line, a secondcapacitor electrode and a power supply are formed simultaneously withthe source and drain electrodes 152 and 154. The data line can extend ina second direction and cross the gate line to define a pixel region. Thesecond capacitor electrode is connected to the drain electrode 154, andthe power supply line is spaced apart from the data line.

Referring to FIG. 3B, a passivation layer 160 is formed on the sourceand drain electrodes 152 and 154 by depositing or applying an insulatingmaterial over substantially all of the substrate 110, and thepassivation layer 160 is selectively removed through a photolithographicprocess using a mask, thereby forming a drain contact hole 160 aexposing the drain electrode 154. The drain contact hole 160 a is formeddirectly over the second contact hole 140 b. Alternatively, the draincontact hole 160 a can be spaced apart from the second contact hole 140b.

The passivation layer 160 can be formed of an inorganic insulatingmaterial such as silicon oxide (SiO₂) and silicon nitride (SiN_(x)) oran organic insulating material such as benzocyclobutene and photo acryl.Beneficially, the passivation layer 160 can be formed of an organicinsulating material to flatten a top surface thereof.

Referring to FIG. 3C, a first electrode material layer is formed on thepassivation layer 160 by depositing a conductive material havingrelatively high work function by a sputtering method, for example, andthe first electrode material layer is selectively removed through aphotolithographic process using a mask, thereby forming a firstelectrode 162 and an auxiliary electrode 164. The first electrode 162 isdisposed in each pixel region and is connected to the drain electrode154 through the drain contact hole 160 a. The auxiliary electrode 164 isspaced apart from the first electrode 162.

The first electrode 162 can include a transparent conductive layer and areflective layer. The transparent conductive layer can be formed of atransparent conductive material such as indium tin oxide (ITO) andindium zinc oxide (IZO), and the reflective layer can be formed ofaluminum-paladium-copper (APC) alloy. For example, the first electrode162 and the auxiliary electrode 164 can have a triple-layered structureof ITO/APC/ITO.

Then, a bank material layer can be formed on the first electrode 162 andthe auxiliary electrode 164 by depositing or applying an insulatingmaterial, and the bank material layer can be selectively removed througha photolithographic process using a mask, thereby forming a bank layer170 having a transmissive hole 170 a and an auxiliary contact hole 170b. The bank layer 170 covers edges of the first electrode 162 and edgesof the auxiliary electrode 164, and the transmissive hole 170 a and theauxiliary contact hole 170 b expose the first electrode 162 and theauxiliary electrode 164, respectively.

Referring to FIG. 3D, a hole injecting material layer 181 a and a holetransporting material layer 182 a are sequentially formed on the banklayer 170, the first electrode 162 and the auxiliary electrode 164 byvacuum depositing a hole injecting material and a hole transportingmaterial over substantially all of the substrate 110. Then, a lightemitting material layer 183 is formed in the transmissive hole 170 a ofthe bank layer 170 by selectively vacuum depositing an organic lightemitting material through a fine metal mask. At this time, the lightemitting material layer 183 can be one of red, green or blue lightemitting material layer, and the other light emitting material layerscan be sequentially formed in the next pixel regions, respectively.

The light emitting material layer 183 of FIG. 3D, for example, can be agreen light emitting material layer of a green pixel region. Therefore,the green light emitting material layer 183 is formed in the green pixelregion by selectively vacuum depositing a green light emitting materialthrough a first fine metal mask, a red light emitting material layer isformed in a red pixel region by selectively vacuum depositing a redlight emitting material through a second fine metal mask, and a bluelight emitting material layer is formed in a blue pixel region byselectively vacuum depositing a blue light emitting material through athird fine metal mask. The order of forming the red, green and bluelight emitting material layers can be changed.

Referring to FIG. 3E, an electron transporting material layer 184 a andan electron injecting material layer 185 a are sequentially formed onthe light emitting material layer 183 by vacuum depositing an electrontransporting material and an electron injecting material oversubstantially all of the substrate 110. Therefore, the hole injectingmaterial layer 181 a, the hole transporting material layer 182 a, thelight emitting material layer 183, the electron transporting materiallayer 184 a and the electron injecting material layer 185 a aresequentially formed on the first electrode 162. The hole injectingmaterial layer 181 a, the hole transporting material layer 182 a, theelectron transporting material layer 184 a and the electron injectingmaterial layer 185 a are sequentially formed on the auxiliary electrode164. For example, the total thickness of the hole injecting materiallayer 181 a, the hole transporting material layer 182 a, the electrontransporting material layer 184 a and the electron injecting materiallayer 185 a on the auxiliary electrode 164 can be less than about 2,000Å.

The hole injecting material layer 181 a, the hole transporting materiallayer 182 a, the electron transporting material layer 184 a and theelectron injecting material layer 185 a formed in each pixel region bythe vacuum deposition method using a fine metal mask, in the OLEDdisplay device according to related art, can result in problemsincluding the degree of accuracy in alignment of the mask and thesubstrate 110 and mass production. In addition, in the OLED displaydevice according to related art. as the size of the substrate increases,the mask can sag.

However, according to the first embodiment of the present disclosure,the hole injecting material layer 181 a, the hole transporting materiallayer 182 a, the electron transporting material layer 184 a and theelectron injecting material layer 185 a are formed over substantiallyall of the substrate 110. Referring to FIG. 3F, common layers of thehole injecting material layer 181 a (refer to FIG. 3E), the holetransporting material layer 182 a (refer to FIG. 3E), the electrontransporting material layer 184 a (refer to FIG. 3E) and the electroninjecting material layer 185 a (refer to FIG. 3E) on the auxiliaryelectrode 164 in the auxiliary contact hole 170 b are melted byinjecting an organic solvent in the auxiliary contact hole 170 b usingan injecting apparatus 197.

Thus, materials of the common layers are dissolved in the organicsolvent, thereby forming a common layer solution 187 a in the auxiliarycontact hole 170 b. At this time, the organic solvent can be injected byan inkjet printing method or a nozzle printing method. The organicsolvent can be one of ethylene glycol, 4-methylanisole, ethyl benzoate,isopropyl alcohol (IPA), acetone, and N-methyl pyrrolidone (NMP).Meanwhile, the hole injecting material layer 181 a (refer to FIG. 3E),the hole transporting material layer 182 a (refer to FIG. 3E), theelectron transporting material layer 184 a (refer to FIG. 3E) and theelectron injecting material layer 185 a (refer to FIG. 3E) on the firstelectrode 162 become a hole injecting layer 181, a hole transportinglayer 182, an electron transporting layer 184 and an electron injectinglayer 185, respectively.

Referring to FIG. 3G, the common layer solution 187 a (refer to FIG. 3F)is dried to volatilize the organic solvent and the materials of thecommon layers dissolved in the organic solvent. In addition, a residuallayer 187 is formed on the auxiliary electrode 164 by the materials ofthe common layers not volatilized. At this time, the residual layer 187has a thickness increasing from a central portion to an edge portionthereof due to a coffee stain effect or coffee ring effect. Thethickness of the edge portion of the residual layer 187 can be 1.1 timesor more than the thickness of the central portion of the residual layer187. Beneficially, the edge portion of the residual layer 187 can bemore than about 10 times as thick as the thickness of the centralportion of the residual layer 187. Here, the thickness of the centralportion of the residual layer 187 can be less than about 200 Å.

For example, the common layer solution 187 a of FIG. 3F can be driedunder the temperature of less than 150 degrees of Celsius for less thanabout 10 minutes. Beneficially, the common layer solution 187 a can bedried under the temperature of 80 to 150 degrees of Celsius, and morebeneficially, under the temperature of 100 to 150 degrees of Celsius. Inthe meantime, to faster dry, the common layer solution 187 a can bedried faster under a vacuum of less than about 50 mTorr.

Referring to FIG. 3H, a second electrode 192 is formed on the electroninjection layer 185 and the residual layer 187 by depositing aconductive material having a relatively low work function oversubstantially all of the substrate 110 by a sputtering method, forexample. The second electrode 192 can be formed of a metallic materialsuch as aluminum, magnesium and silver. The second electrode 192 has arelatively thin thickness such that light is transmitted therethrough.

Here, the second electrode 192 is electrically connected to theauxiliary electrode 164 through the auxiliary contact hole 170 b. Thesecond electrode 192 can directly contact the auxiliary electrode 164 orindirectly contact the auxiliary electrode 164 through the residuallayer 187. Although the second electrode 192 is connected to theauxiliary electrode 164 through the residual layer 187, the secondelectrode 192 is electrically connected to the auxiliary electrode 164because the thickness of the central portion of the residual layer 187is less than about 200 Å.

The hole injecting layer 181, the hole transporting layer 182, the lightemitting material layer 183, the electron transporting layer 184 and theelectron injecting layer 185 form a light emitting layer 180, and thefirst electrode 162, the light emitting layer 180 and the secondelectrode 192 constitute an organic light emitting diode. The firstelectrode 162 functions as an anode, and the second electrode 192 servesas a cathode. Here, the OLED display device is a top emission type inwhich light from the light emitting layer 180 is output to the outsidethrough the second electrode 192.

In the OLED display device according to the first embodiment of thepresent invention, the auxiliary electrode 164 is connected to thesecond electrode 192, and the resistance of the second electrode 192 islowered. At this time, the auxiliary electrode 164 is formed through thesame process as the first electrode 162, and an additional process forforming the auxiliary electrode 164 is not required. Additionally, thecommon layers on the auxiliary electrode 164 are removed by the organicsolvent, and the auxiliary electrode 164 and the second electrode 192can be electrically connected to each other through a simple process.

In the first embodiment of the present disclosure, the electroninjecting material layer 185 a (refer to FIG. 3E), the electrontransporting material layer 184 a (refer to FIG. 3E), the holetransporting material layer 182 a (of FIG. 3E) and the hole transportingmaterial layer 181 a (of FIG. 3E) in the auxiliary contact hole 170 bare completely melted and then dried, thereby electrically connectingthe second electrode 192 and the auxiliary electrode 164. Alternatively,the electron injecting material layer 185 a (refer to FIG. 3E), theelectron transporting material layer 184 a (refer to FIG. 3E), the holetransporting material layer 182 a (refer to FIG. 3E) and the holetransporting material layer 181 a (refer to FIG. 3E) in the auxiliarycontact hole 170 b can be partially melted and then dried, therebyelectrically connecting the second electrode 192 and the auxiliaryelectrode 164.

Next, FIG. 4 is a cross-sectional view of an OLED display deviceaccording to a second embodiment of the present disclosure. The displaydevice of FIG. 4 has the same structure as the display device of FIG. 2except for the auxiliary electrode. The same reference numbers will beused to refer to the same parts as the display device of FIG. 2, andexplanations for the same parts will be omitted.

A first dummy electrode 134 is formed on the gate insulating layer 130.The first dummy electrode 134 can be formed of the same material andthrough the same process as the gate electrode 132. Next, the interinsulating layer 140 covers the first dummy electrode 134, and the interinsulating layer 140 further includes a third contact hole 140 cexposing the first dummy electrode 134. A second dummy electrode 156 isformed on the inter insulating layer 140. The second dummy electrode 156overlaps the first dummy electrode 134 and contacts the first dummyelectrode 134 through the third contact hole 140 c. The second dummyelectrode 156 can be formed of the same material and through the sameprocess as the source and drain electrodes 152 and 154.

Next, the passivation layer 160 covers the second dummy electrode 156and has a fourth contact hole 160 b exposing the second dummy electrode156. An auxiliary electrode 164 is formed on the passivation layer 160.The auxiliary electrode 164 overlaps the second dummy electrode 156 andcontacts the second dummy electrode 156 through the fourth contact hole160 b.

The bank layer 170 is formed on the auxiliary electrode 164. The banklayer 170 has an auxiliary contact hole 170 b exposing the auxiliaryelectrode 164. The residual layer 187 is formed on the auxiliaryelectrode 164 by melting and drying the common layers. The secondelectrode 192 is formed over substantially all of the substrate 110 andis electrically connected to the auxiliary electrode 164 through theauxiliary contact hole 170 b. The second electrode 192 can directlycontact the auxiliary electrode 164 or indirectly contact the auxiliaryelectrode 164 through the residual layer 187.

The auxiliary electrode 164 can extend in the first direction and thesecond direction over the substrate 110 and include an openingcorresponding to each pixel region to have a lattice shape. The firstdummy electrode 134 can extend in the first direction, that is, parallelto the gate line and overlap the auxiliary electrode 164. The seconddummy electrode 156 can extend in the second direction, that is,parallel to the data line and overlap the auxiliary electrode 164.

In the OLED display device according to the second embodiment of thepresent disclosure, the first and second dummy electrodes 134 and 156are further formed and are electrically connected to the auxiliaryelectrode 164 and the second electrode 192. Therefore, the resistance ofthe second electrode 192 is further lowered as compared to the firstembodiment, and the non-uniform brightness is improved. Here, one of thefirst and second dummy electrodes 134 and 156 can be omitted.

Next, FIG. 5 is a cross-sectional view of an OLED display deviceaccording to a third embodiment of the present disclosure. The displaydevice of FIG. 5 has the same structure as the display device of FIG. 2except for the light emitting layer. The same reference numbers will beused to refer to the same parts as the display device of FIG. 2, andexplanations for the same parts will be omitted.

A light emitting layer 180 a is formed on the first electrode 162exposed by the transmissive hole 170 a of the bank layer 170. The lightemitting layer 180 a includes a hole injecting layer 181, a holetransporting layer 182, a white light emitting material layer 183 a, anelectron transporting layer 184, and an electron injecting layer 185sequentially layered on the first electrode 162. Here, the holeinjecting layer 181, the hole transporting layer 182, the white lightemitting material layer 183 a, the electron transporting layer 184 andthe electron injecting layer 185 are formed over substantially all ofthe substrate 110 excluding the auxiliary contact hole 170 b.

The white light emitting material layer 183 a emits white light. Thewhite light emitting material layer 183 a can include a single layer ormore than two light emitting material layers emitting different colorlight. For example, the white light emitting material layer 183 a canhave a layered structure of red, green and blue light emitting materiallayers.

The hole injecting layer 181, the hole transporting layer 182, the whitelight emitting material layer 183 a, the electron transporting layer 184and the electron injecting layer 185 can be formed over substantiallyall of the substrate 110 by sequentially vacuum depositing a holeinjecting material, a hole transporting material, a white light emittingmaterial, an electron transporting material and an electron injectingmaterial without a fine metal mask.

A residual layer 187 b is formed in the auxiliary contact hole 170 b.The residual layer 187 b has a thickness increasing from a centralportion to an edge portion thereof in the auxiliary contact hole 170 b.The thickness of the edge portion of the residual layer 187 b can be 1.1times or more than the thickness of the central portion of the residuallayer 187 b. Beneficially, the thickness of the edge portion of theresidual layer 187 can be more than 10 times as thick as the thicknessof the central portion of the residual layer 187 b. For example, thethickness of the central portion of the residual layer 187 b can be lessthan 300 Å.

The OLED display device according to the third embodiment of the presentdisclosure includes red, green and blue color filters (not shown). Thecolor filters can be formed over the substrate 110 or over a counterpartsubstrate attached with the substrate 110 later.

In the meantime, the OLED display device according to the thirdembodiment of the present disclosure can further include the first andsecond dummy electrodes connected to the auxiliary electrode 164similarly to the display device of FIG. 4.

Next, FIG. 6 and FIG. 7 are cross-sectional views of an OLED displaydevice according to a fourth embodiment of the present disclosure. FIG.6 shows a structure corresponding to a red or green pixel region, andFIG. 7 shows a structure corresponding to a blue pixel region. Here, thesimilar reference numbers will be used to refer to the similar parts orsame parts as the first embodiment, and explanations for the same partswill be simplified.

A semiconductor layer 222 is formed in each pixel region on aninsulating substrate 210. A gate insulating layer 230 of an insulatingmaterial is formed over substantially all of the substrate 210.

A gate electrode 232 of a conductive material such as metal is formed onthe gate insulating layer 230 to correspond to the semiconductor layer222. In addition, a gate line and a first capacitor electrode can beformed on the gate insulating layer 230. The gate line extends in afirst direction, and the first capacitor electrode is connected to thegate electrode 232.

An inter insulating layer 240 of an insulating material is formed on thegate electrode 232 over substantially all of the substrate 210. Theinter insulating layer 240 has first and second contact holes 240 a and240 b exposing top surfaces of both sides of the semiconductor layer222. The first and second contact holes 240 a and 240 b are spaced apartfrom the gate electrode 232, and the gate electrode 232 is disposedbetween the first and second contact holes 240 a and 240 b. The firstand second contact holes 240 a and 240 b also can be formed in the gateinsulating layer 230.

A source electrode 252 and a drain electrode 254 of a conductivematerial such as metal are formed on the inter insulating layer 240. Inaddition, a data line, a power supply line and a second capacitorelectrode can be formed on the inter insulating layer 240. The data lineand the power supply line extend in a second direction.

The source and drain electrodes 252 and 254 are spaced apart from eachother with respect to the gate electrode 232. The source and drainelectrodes 252 and 254 contact both sides of the semiconductor layer 222through the first and second contact holes 240 a and 240 b,respectively. The data line crosses the gate line to define a pixelregion, and the power supply line is spaced apart from the data line.The second capacitor electrode is connected to the drain electrode 254and overlaps the first capacitor electrode to form a storage capacitorwith the inter insulating layer 240 therebetween as a dielectricsubstance.

In the meantime, the semiconductor layer 222, the gate electrode 232,the source electrode 252 and the drain electrode 254 constitute a thinfilm transistor. A passivation layer 260 of an insulating material isformed on the source and drain electrodes 252 and 254 over substantiallyall of the substrate 210. The passivation layer 260 has a flat topsurface and has a drain contact hole 260 a exposing the drain electrode254. Although the drain contact hole 260 a is formed directly over thesecond contact hole 240 b (refer to FIGS. 6 and 7), the drain contacthole 260 a can be spaced apart from the second contact hole 240 b.

A first electrode 262 of a conductive material having relatively highwork function is formed on the passivation layer 260. The firstelectrode 262 is disposed in each pixel region and contacts the drainelectrode 254 through the drain contact hole 260 a. For example, thefirst electrode 262 can be formed of a transparent conductive materialsuch as indium tin oxide (ITO) and indium zinc oxide (IZO).

Meanwhile, the first electrode 262 can further include a reflectivelayer of an opaque conductive material. For example, the reflectivelayer can be formed of aluminum-paladium-copper (APC) alloy, and thefirst electrode 262 can have a triple-layered structure of ITO/APC/ITO.

Additionally, an auxiliary electrode 264 is formed on the passivationlayer 260 and spaced apart from the first electrode 262. The auxiliaryelectrode 264 can be formed of the same material as the first electrode262. The auxiliary electrode 264 can extend in the first direction inwhich the gate line extends and in the second direction in which thedata line and the power supply line extend. In addition, the auxiliaryelectrode 264 can include an opening corresponding to each pixel regionto have a lattice shape. The first electrode 262 can be disposed in theopening of the auxiliary electrode 264.

A bank layer 270 of an insulating material is formed on the firstelectrode 262 and the auxiliary electrode 264. The bank layer 270 has atransmissive hole 270 a and an auxiliary contact hole 270 b. The banklayer 270 covers edges of the first electrode 262 and edges of theauxiliary electrode 264. The transmissive hole 270 a exposes the firstelectrode 262, and the auxiliary contact hole 270 b exposes theauxiliary electrode 264.

A light emitting layer 280 a or 280 b is formed on the first electrode262 exposed by the transmissive hole 270 a of the bank layer 270. Afirst light emitting layer 280 a is formed in the red or green pixelregion, and a second light emitting layer 280 b is formed in the bluepixel region.

The first light emitting layer 280 a includes a hole injecting layer281, a hole transporting layer 282, a first light emitting materiallayer 283, a second light emitting material layer 284, an electrontransporting layer 285, and an electron injecting layer 286 sequentiallylayered on the first electrode 262. The second light emitting layer 280b includes a hole injecting layer 281, a hole transporting layer 282, asecond light emitting material layer 284, an electron transporting layer285, and an electron injecting layer 286 sequentially layered on thefirst electrode 262. The first light emitting material layer 283 can bea red or green light emitting material layer, and the second lightemitting material layer 284 can be a blue light emitting material layer.

Here, the hole injecting layer 281, the hole transporting layer 282 andthe first light emitting material layer 283 are formed only in thetransmissive hole 270 a, and the second light emitting material layer284, the electron transporting layer 285 and the electron injectinglayer 286 are formed over substantially all of the substrate 210excluding the auxiliary contact hole 270 b.

Namely, the second light emitting material layer 284 is formed in thered, green and blue pixel regions. In the red and green pixel regions,the second light emitting material layer 284 functions as a holeblocking layer, and in the blue pixel region, the second light emittingmaterial layer 284 serves as a blue light emitting material layer.

In the meantime, a residual layer 287 is formed in the auxiliary contacthole 270 b. The residual layer 287 has a thickness increasing from acentral portion to an edge portion thereof in the auxiliary contact hole270 b. The thickness of the edge portion of the residual layer 287 canbe 1.1 times or more than the thickness of the central portion of theresidual layer 287. Beneficially, the thickness of the edge portion ofthe residual layer 287 can be more than 10 times as thick as thethickness of the central portion of the residual layer 287. For example,the thickness of the central portion of the residual layer 287 can beless than 50 Å.

A second electrode 292 of a conductive material having a relatively lowwork function is formed on the light emitting layer 280 a or 280 b oversubstantially all of the substrate 210. Here, the second electrode 292can be formed of aluminum (Al), magnesium (Mg), silver (Ag) or theiralloy. The second electrode 292 can have a relatively thin thicknesssuch that light is transmitted therethrough. At this time, thetransmittance of the second electrode 292 can be about 45 to 50%.

The second electrode 292 is electrically connected to the auxiliaryelectrode 264 through the auxiliary contact hole 270 b. The secondelectrode 292 can directly contact the auxiliary electrode 264 orindirectly contact the auxiliary electrode 264 through the residuallayer 287.

The first electrode 262, the light emitting layer 280 a or 280 b and thesecond electrode 292 constitute an organic light emitting diode. Thefirst electrode 262 functions as an anode, and the second electrode 292serves as a cathode. Here, the OLED display device is a top emissiontype in which light from the light emitting layer 280 a or 280 b isoutput to the outside through the second electrode 292.

In the OLED display device according to the fourth embodiment of thepresent disclosure, the second electrode 292 is connected to theauxiliary electrode 264, and the resistance of the second electrode 292is lowered. At this time, the second electrode 292 can be connected tothe auxiliary electrode 264 through a simple process by removing commonlayers in the auxiliary contact hole 270 b using an organic solvent.

The OLED display device according to the fourth embodiment of thepresent disclosure can further include the first and second dummyelectrodes connected to the auxiliary electrode 264 similarly to thedisplay device of FIG. 4.

Next, FIGS. 8A to 8F are cross-sectional views of an OLED display devicein steps of fabricating the display device according to the fourthembodiment of the present disclosure. FIGS. 8A to 8F show a structurecorresponding to the red or green pixel region of FIG. 6. Here,explanations for the similar steps as in the first embodiment will besimplified.

Referring to FIG. 8A, a semiconductor material layer is formed on aninsulating substrate 210 by depositing a semiconductor material, and thesemiconductor material layer is selectively removed through aphotolithographic process using a mask, thereby forming a semiconductorlayer 222. Next, a gate insulating layer 230 is formed on thesemiconductor layers 222 by depositing an insulating material oversubstantially all of the substrate 210 by, for example, a chemical vapordeposition method.

Then, a first conductive material layer is formed on the gate insulatinglayer 230 by depositing a conductive material such as metal. Inparticular, the first conductive material layer can be formed on thegate insulating layer 230 via, for example, a sputtering method. Thefirst conductive material layer is selectively removed through aphotolithographic process using a mask, thereby forming a gate electrode232. The gate electrode 232 has a narrower width than the semiconductorlayer 222 and is disposed to correspond to a central part of thesemiconductor layer 222. Meanwhile, a first capacitor electrode and agate line are formed simultaneously with the gate electrode 232. Thefirst capacitor electrode can be connected to the gate electrode 232,and the gate line can extend in a first direction.

Next, an inter insulating layer 240 is formed on the gate electrode 232by depositing or applying an insulating material over substantially allof the substrate 210, and the inter insulating layer 240 and the gateinsulating layer 230 are selectively removed through a photolithographicprocess using a mask, thereby forming first and second contact holes 240a and 240 b. The first and second contact holes 240 a and 240 b exposetop surfaces of both sides of the semiconductor layer 222, respectively.The first and second contact holes 240 a and 240 b are spaced apart fromthe gate electrode 232, and the gate electrode 232 is disposed betweenthe first and second contact holes 240 a and 240 b.

Next, a second conductive material layer is formed on the interinsulating layer 240 by depositing a conductive material such as metalby a sputtering method, for example, and the second conductive materiallayer is selectively removed through a photolithographic process using amask, thereby forming source and drain electrodes 252 and 254. Thesource and drain electrodes 252 and 254 are spaced apart from each otherwith respect to the gate electrode 232. The source and drain electrodes252 and 254 contact both sides of the semiconductor layer 222 throughthe first and second contact holes 240 a and 240 b, respectively.

In the meantime, a data line, a second capacitor electrode and a powersupply line are formed simultaneously with the source and drainelectrodes 252 and 254. Although not shown in the figure, the data lineextends in a second direction and crosses the gate line to define apixel region. The second capacitor electrode is connected to the drainelectrode 254, and the power supply line is spaced apart from the dataline.

Next, a passivation layer 260 is formed on the source and drainelectrodes 252 and 254 by depositing or applying an insulating materialover substantially all of the substrate 210. In addition, thepassivation layer 260 is selectively removed through a photolithographicprocess using a mask, thereby forming a drain contact hole 260 aexposing the drain electrode 254.

Next, a first electrode material layer can be formed on the passivationlayer 260 by depositing a conductive material having relatively highwork function. In particular, the first electrode material layer can beformed on the passivation layer 260 by, for example, a sputteringmethod, for example. The first electrode material layer is selectivelyremoved through a photolithographic process using a mask, therebyforming a first electrode 262 and an auxiliary electrode 264. The firstelectrode 262 is disposed in each pixel region and is connected to thedrain electrode 254 through the drain contact hole 260 a. The auxiliaryelectrode 264 is spaced apart from the first electrode 262.

The first electrode 262 can include a transparent conductive layer and areflective layer. The transparent conductive layer can be formed of atransparent conductive material such as indium tin oxide (ITO) andindium zinc oxide (IZO), and the reflective layer can be formed ofaluminum-paladium-copper (APC) alloy. For example, the first electrode262 and the auxiliary electrode 264 can have a triple-layered structureof ITO/APC/ITO.

Then, a bank material layer (not shown) is formed on the first electrode262 and the auxiliary electrode 264 by depositing or applying aninsulating material. The bank material layer is selectively removedthrough a photolithographic process using a mask, thereby forming a banklayer 270 having a transmissive hole 270 a and an auxiliary contact hole270 b. The bank layer 270 covers edges of the first electrode 262 andedges of the auxiliary electrode 264, and the transmissive hole 270 aand the auxiliary contact hole 270 b expose the first electrode 262 andthe auxiliary electrode 264, respectively.

Referring to FIG. 8B, a hole injecting layer 281, a hole transportinglayer 282 and a first light emitting material layer 283 are sequentiallyformed on the first electrode 262 exposed by the transmissive hole 270 aby applying a hole injecting material, a hole transporting material anda first light emitting material through a solution process using a firstinjecting apparatus 297. The solution process can include a printingmethod or a coating method. For example, the solution process caninclude an inkjet printing method or a nozzle printing method.

Here, the first light emitting material layer 283 of FIG. 8B can be oneof red and green light emitting material layers, and another lightemitting material layer can be formed in the next pixel region. Forinstance, the first light emitting material layer 283 of FIG. 8B can bea green light emitting material layer of the green pixel region. Thus,the green light emitting material layer 283 is formed in the green pixelregion by applying a green light emitting material through a solutionprocess. A red light emitting material layer can be formed in the redpixel region by applying a red light emitting material through asolution process. The order of forming the red and green light emittingmaterial layers can be changed.

Referring to FIG. 8C, a second light emitting material deposition layer284 a is formed on the first light emitting material layer 283 by vacuumdepositing a second light emitting material, i.e., a blue light emittingmaterial over substantially all of the substrate 210. Then, an electrontransporting material layer 285 a and an electron injecting materiallayer 286 are sequentially formed on the second light emitting materialdeposition layer 284 a by vacuum depositing an electron transportingmaterial and an electron injecting material over substantially all ofthe substrate 210.

Therefore, in each of the red and green pixel regions, the holeinjecting layer 281, the hole transporting layer 282, the first lightemitting material layer 283, the second light emitting materialdeposition layer 284 a, the electron transporting material layer 285 aand the electron injecting material layer 286 a are sequentially formedon the first electrode 262, and common layers of the second lightemitting material deposition layer 284 a, the electron transportingmaterial layer 285 a, and the electron injecting material layer 286 aare sequentially formed on the auxiliary electrode 264. For example, thetotal thickness of the second light emitting material deposition layer284 a, the electron transporting material layer 285 a and the electroninjecting material layer 286 a on the auxiliary electrode 264 can beless than about 500 Å.

Meanwhile, in the blue pixel region, the hole injecting layer 281, thehole transporting layer 282, the second light emitting materialdeposition layer 284 a, the electron transporting material layer 285 aand the electron injecting material layer 286 a are sequentially formedon the first electrode 262, and the second light emitting materialdeposition layer 284 a, the electron transporting material layer 285 a,and the electron injecting material layer 286 a are sequentially formedon the auxiliary electrode 264.

In the fourth embodiment of the present disclosure, the hole injectinglayer 281, the hole transporting layer 282, and the first light emittingmaterial layer 283 of red or green are formed through the solutionprocess, and the second light emitting material deposition layer 284 aof blue, the electron transporting material layer 285 a and the electroninjecting material layer 286 a are formed over substantially all of thesubstrate 210 by the vacuum deposition method. Thus, problems such asthe degree of accuracy in alignment of the mask and the substrate 210and mass production can be prevented. In addition, it is prevented thatthe mask sags. The light emitting layer 280 a of FIG. 6 or 280 b of FIG.7 can be uniformly formed even if the size of the substrate 210increases.

Referring to FIG. 8D, the common layers of the electron injectingmaterial layer 286 a of FIG. 8C, the electron transporting materiallayer 285 a of FIG. 8C, and the second light emitting materialdeposition layer 284 a of FIG. 8C on the auxiliary electrode 264 in theauxiliary contact hole 270 b are melted by injecting an organic solventin the auxiliary contact hole 270 b using a second injecting apparatus299. Thus, materials of the common layers are dissolved in the organicsolvent, thereby forming a common layer solution 287 a in the auxiliarycontact hole 270 b. At this time, the organic solvent can be injected byan inkjet printing method or a nozzle printing method.

The organic solvent can be one of ethylene glycol, 4-methylanisole,ethyl benzoate, isopropyl alcohol (IPA), acetone, and N-methylpyrrolidone (NMP). The second light emitting material deposition layer284 a of FIG. 8C, the electron transporting material layer 285 a of FIG.8C and the electron injecting material layer 286 a of FIG. 8C on thefirst electrode 262 become a second light emitting material layer 284,an electron transporting layer 285 and an electron injecting layer 286,respectively.

Referring to FIG. 8E, the common layer solution 287 a of FIG. 8D isdried to volatilize the organic solvent and the materials of the commonlayers dissolved in the organic solvent, and a residual layer 287 isformed on the auxiliary electrode 264 by the materials of the commonlayers not volatilized.

At this time, the residual layer 287 has a thickness increasing from acentral portion to an edge portion thereof due to a coffee stain effector coffee ring effect. The thickness of the edge portion of the residuallayer 287 can be 1.1 times or more than the thickness of the centralportion of the residual layer 287. Beneficially, the edge portion of theresidual layer 287 can be more than about 10 times as thick as thethickness of the central portion of the residual layer 287. Here, thethickness of the central portion of the residual layer 287 can be lessthan about 50 Å.

Referring to FIG. 8F, a second electrode 292 is formed on the electroninjection layer 286 and the residual layer 287 by depositing aconductive material having relatively low work function oversubstantially all of the substrate 210 by a sputtering method, forexample. The second electrode 292 can be formed of a metallic materialsuch as aluminum, magnesium and silver. The second electrode 292 has arelatively thin thickness such that light is transmitted therethrough.

Here, the second electrode 292 is electrically connected to theauxiliary electrode 264 through the auxiliary contact hole 270 b. Thesecond electrode 292 can directly contact the auxiliary electrode 264 orindirectly contact the auxiliary electrode 164 through the residuallayer 287. Although the second electrode 292 is connected to theauxiliary electrode 264 through the residual layer 287, the secondelectrode 292 is electrically connected to the auxiliary electrode 264because the thickness of the central portion of the residual layer 287is less than about 50 Å. Here, the OLED display device is a top emissiontype in which light from the first light emitting layer 280 a is outputto the outside through the second electrode 292.

In the OLED display device according to the fourth embodiment of thepresent invention, the auxiliary electrode 264 is connected to thesecond electrode 292, and the resistance of the second electrode 292 islowered. At this time, the auxiliary electrode 264 is formed through thesame process as the first electrode 262, and an additional process forforming the auxiliary electrode 264 is not required. Additionally, thecommon layers on the auxiliary electrode 264 are removed by the organicsolvent, and the auxiliary electrode 264 and the second electrode 292can be electrically connected to each other through a simple process.

In the fourth embodiment of the present disclosure, the electroninjecting material layer 286 a of FIG. 8C, the electron transportingmaterial layer 285 a of FIG. 8C, and the second light emitting materialdeposition layer 284 a of FIG. 8C in the auxiliary contact hole 270 bare completely melted and then dried, thereby electrically connectingthe second electrode 292 and the auxiliary electrode 264. Alternatively,the electron injecting material layer 286 a of FIG. 8C, the electrontransporting material layer 285 a of FIG. 8C, and the second lightemitting material deposition layer 284 a of FIG. 8C in the auxiliarycontact hole 270 b can be partially melted and then dried, therebyelectrically connecting the second electrode 292 and the auxiliaryelectrode 264.

According to embodiments of the OLED display device of the presentdisclosure, light emitting from the light emitting layer is output tothe outside through the second electrode. As a result, the OLED displaydevice in which light is output to the outside through the secondelectrode has a relatively high aperture ratio, large size and highdefinition. Because the second electrode is connected to the auxiliaryelectrode, the resistance of the second electrode is lowered, and thebrightness is uniform.

In further detail, according to embodiments of the present disclosure,the manufacturing process of the OLED display device is simplified dueto the auxiliary electrode being formed of the same material and on thesame layer as the first electrode. Also, according to embodiments of thepresent disclosure, the manufacturing process of the OLED display deviceis simplified because the common layers on the auxiliary electrode areremoved using the organic solvent, and the second electrode is connectedto the auxiliary electrode. Accordingly, the manufacturing costs of theOLED display device are also reduced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in a display device of thepresent disclosure without departing from the sprit or scope of theembodiments. Thus, it is intended that the present disclosure covers themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

1. An organic light emitting diode display device comprising: a substrate; a thin film transistor on the substrate; a first electrode on the thin film transistor and connected to a drain electrode of the thin film transistor; an auxiliary electrode on a same layer as the first electrode; a bank layer covering edges of the first electrode and edges of the auxiliary electrode and having a transmissive hole corresponding to the first electrode and an auxiliary contact hole corresponding to the auxiliary electrode; a light emitting layer on the first electrode in the transmissive hole; a residual layer on the auxiliary electrode in the auxiliary contact hole, wherein a thickness of a central portion of the residual layer is smaller than a thickness of an edge portion of the residual layer; and a second electrode on the light emitting layer and the residual layer.
 2. The organic light emitting diode display device of claim 1, wherein the thickness of the edge portion of the residual layer is 1.1 times or more than the thickness of the central portion of the residual layer.
 3. The organic light emitting diode display device of claim 1, wherein the light emitting layer includes a hole injecting layer, a hole transporting layer, a light emitting material layer, an electron transporting layer and an electron injecting layer, and wherein the hole injecting layer, the hole transporting layer, the electron transporting layer and the electron injecting layer are disposed over the bank layer.
 4. The organic light emitting diode display device of claim 3, wherein the light emitting material layer is formed on the first electrode corresponding to the transmissive hole of the bank layer.
 5. The organic light emitting diode display device of claim 1, wherein the light emitting layer of a first pixel region includes a hole injecting layer, a hole transporting layer, a first light emitting material layer, a second light emitting material layer, an electron transporting layer and an electron injecting layer, and wherein the second light emitting material layer, the electron transporting layer and the electron injecting layer are disposed over the bank layer.
 6. The organic light emitting diode display device of claim 5, wherein the light emitting layer of a second pixel region adjacent to the first pixel region includes a hole injecting layer, a hole transporting layer, a second light emitting material layer, an electron transporting layer and an electron injecting layer.
 7. The organic light emitting diode display device of claim 6, wherein the first light emitting material layer of the first pixel region is a red or green light emitting material layer, and the second light emitting material layer of the second pixel region is a blue light emitting material layer.
 8. The organic light emitting diode display device of claim 1, further comprising: a first dummy electrode on a same layer as a gate electrode of the thin film transistor; and a second dummy electrode on a same layer as the drain electrode of the thin film transistor, wherein the first and second dummy electrodes are electrically connected to the auxiliary electrode.
 9. The organic light emitting diode display device of claim 1, wherein the second electrode is electrically connected to a center of the auxiliary electrode.
 10. (canceled)
 11. A method of fabricating an organic light emitting diode display device, the method comprising: forming a thin film transistor on a substrate; forming a passivation layer on the thin film transistor; forming a first electrode and an auxiliary electrode on the passivation layer, the first electrode connected to a drain electrode of the thin film transistor, and the auxiliary electrode spaced apart from the first electrode; forming a bank layer having a transmissive hole exposing the first electrode and an auxiliary contact hole exposing the auxiliary electrode; sequentially forming a hole injecting material layer and a hole transporting material layer over substantially all of the substrate including the bank layer; forming a light emitting material layer on the hole transporting material layer corresponding to the transmissive hole; sequentially forming an electron transporting material layer and an electron injecting material layer over substantially all of the substrate including the light emitting material layer; melting and drying the electron injecting material layer, the electron transporting material layer, the hole transporting material layer and the hole injecting material layer corresponding to the auxiliary contact hole using an organic solvent, thereby forming a hole injecting layer, a hole transporting layer, an electron transporting layer and an electron injecting layer corresponding to the light emitting material layer and forming a residual layer on the auxiliary electrode in the auxiliary contact hole, wherein a thickness of a central portion of the residual layer is smaller than a thickness of an edge portion of the residual layer; and forming a second electrode on the electron injecting layer and the residual layer.
 12. The method of claim 11, wherein the hole injecting material layer, the hole transporting material layer, the light emitting material layer, the electron transporting material layer and the electron injecting material layer are formed by a vacuum deposition method.
 13. The method of claim 11, wherein the light emitting material layer is formed over substantially all of the substrate, and wherein forming the residual layer includes melting and drying the light emitting material layer corresponding to the auxiliary contact hole using the organic solvent.
 14. The method of claim 11, wherein the organic solvent is injected by an inkjet printing method or a nozzle printing method.
 15. The method of claim 11, wherein the second electrode is electrically connected to a center of the auxiliary electrode.
 16. The method of claim 11, wherein the thickness of the edge portion of the residual layer is 1.1 times or more than the thickness of the central portion of the residual layer.
 17. A method of fabricating an organic light emitting diode display device, the method comprising: forming a thin film transistor on a substrate; forming a passivation layer on the thin film transistor; forming a first electrode and an auxiliary electrode on the passivation layer, the first electrode connected to a drain electrode of the thin film transistor, and the auxiliary electrode spaced apart from the first electrode; forming a bank layer having a transmissive hole exposing the first electrode and an auxiliary contact hole exposing the auxiliary electrode; sequentially forming a hole injecting layer, a hole transporting layer and a first light emitting material layer on the first electrode exposed by the transmissive hole; sequentially forming a second light emitting material deposition layer, an electron transporting material layer and an electron injecting material layer over substantially all of the substrate including the first light emitting material layer; melting and drying the electron injecting material layer, the electron transporting material layer, and the second light emitting material deposition layer corresponding to the auxiliary contact hole using an organic solvent, thereby forming a second light emitting material layer, an electron transporting layer and an electron injecting layer corresponding to the first light emitting material layer and forming a residual layer on the auxiliary electrode in the auxiliary contact hole, wherein a thickness of a central portion of the residual layer is smaller than a thickness of an edge portion of the residual layer; and forming a second electrode on the electron injecting layer and the residual layer.
 18. The method of claim 17, wherein the hole injecting layer, the hole transporting layer and the first light emitting material layer are formed through a solution process, and the second light emitting material deposition layer, the electron transporting material layer and the electron injecting material layer are formed by a vacuum deposition method.
 19. The method of claim 17, wherein the organic solvent is injected by an inkjet printing method or a nozzle printing method.
 20. The method of claim 17, wherein the second electrode is electrically connected to a center of the auxiliary electrode, and wherein the thickness of the edge portion of the residual layer is 1.1 times or more than the thickness of the central portion of the residual layer. 